Wash the areas around the tattoo, wash tattoo itself lightly. Scrubbing your skin clean creating friction will start to tear the ink from your skin.
Try covering your tattoo with petroleum jelly, which can act as a sealant or a water-based lotion which may help it last longer.
Baby powder, corn starch, or talcum powder on the tattoo may also help increase the life of the tattoo by soaking up the natural oils on your skin that would start to break down the ink in your tattoo. Try not to inhale these powders, as they can be harmful to your lungs.